The general objective of this study is to develop and evaluate sensitive, reliable and practical methods for the quantitative detection of enteric viruses in oysters and clams and in the estuarine waters and sediments from which they are harvested. The specific objectives are (1) to further improve and then evaluate a new method for concentrating enteroviruses from oysters and to extend this methodology to the detection of other enteric viruses, including reoviruses, adenoviruses and parvoviruses in both oysters and clams; (2) to further improve and evaluate a new method for concentrating small quantities of enteoviruses from large volumes of turbid estuarine waters and to extend this methodology to the detection of reoviruses, adenoviruses and parvoviruses; (3) to develop and evaluate quantitative methods for recovering enteric viruses from estuarine sediments. These enteric virus concentration and recovery methods will then be evaluated in field studies on the detection of naturally occurring enteric viruses in shellfish and estuarine waters and sediments from both polluted areas. Total and fecal coliform levels will also be measured in an attempt to correlate enteric virus levels with these bacterial parameters of sanitary quality. Successful completion of the objectives of this study will result in effective methods for efficient and quantitative detection of enteric viruses in shellfish and their habitat. Such methods are needed to determine the adequacy of present bacteriological criteria for the sanitary quality of shellfish and their harvesting waters and to determine if routine or periodic virological monitoring of shellfish and shellfish harvesting waters is feasible, practical or necessary.